Tagged Questions

Particle physics is the study of the fundamental forces of nature as they are embodied in the interactions of elementary and composite particles at high energies and short time and distance scales.

learn more… | top users | synonyms (1)

12
votes
1answer
251 views

What do we see while watching light? Waves or particles?

Im trying to understand quantum physics. I'm pretty much familiar with it but I can't decide what counts observing to cause particle behave (at least when it's about lights). So the question is what ...
0
votes
0answers
10 views

Techni-Higgs Particle

I read online that a professor from Denmark alleged that the particle that was found in Cern is not necessarily Higgs Boson, it has many characteristics that match with the "god particle" , but it ...
0
votes
1answer
56 views

How to explain electrons' interaction via the weak force?

What is the piece of theory which dictates that electrons interact via the weak force with other electrons and protons, and how can this force be understood in terms of what I am more familiar with ...
7
votes
0answers
47 views

Why is the energy of particles in accelerators much higher than the energy of the particles they are trying to find?

I have been wondering. In the LHC, or other particle accelerators for that matter, they are colliding particles with energies above TeV. The LHC is going to be 14 TeV or something like that the next ...
5
votes
4answers
795 views

What are Quarks made of and will they ever decay to this? [duplicate]

What is it that quarks are actually made of? Will they decay into this substance? As the up and down quarks are the lightest type of quark do they not decay? I was thinking that if this could happen, ...
7
votes
2answers
72 views

Can an elementary particle be reduced to its properties?

For instance, is an up quark merely its particular mass, 2/3 electrical charge and 1/2 spin? I was wondering if there was a 1:1 correspondence with a particle and its properties, but I noticed a gluon ...
2
votes
1answer
59 views

How does interpreting negative energy electrons as positrons solve the negative energy problem?

How does interpreting negative energy electrons as positive energy positrons solve the negative energy problem? How does change of “interpretation” without fixing the mathematics have such a profound ...
2
votes
1answer
21 views

How doesn't an ionization chamber leak?

I'm sure my understanding of an ionization chamber is incorrect, so please point out the error. Suppose we are using an sealed ionization chamber to detect the energies (trajectories) of a particular ...
0
votes
1answer
32 views

About fundamental particles in hydrogen isotope [closed]

I've studied that the job of a neutron is to hold up protons. If that is the case, then what is the use of neutron in the deuterium atom?
1
vote
0answers
14 views

Upper bound to annihilation cross section into heavy particles

For a process in which two relativistic particles annihilate to produce two or more heavy(er) particles of mass $M$: Is it true that the cross section $\sigma_{ann}$ cannot be larger than ...
0
votes
1answer
26 views

If matter and antimatter were produced equally during the big bang, where is the rest of the antimatter? [duplicate]

As far as my understanding goes, during the 'Big Bang' equal amounts of matter and antimatter (matter's oppositely charged twin) were produced, and the physical matter that remains within this ...
0
votes
1answer
50 views

How positron and electron annihilate forming photons? [duplicate]

Electron is a particle with momentum $p$ and it spins up. Positron is its antiparticle having momentum $-p$ and it spins down. "A positron is an electron travelling backwards in time" said by Feynman. ...
4
votes
0answers
81 views

Are the left-chiral and right-chiral yukawa couplings equal?

I guess another way to ask this is: Does the "physical electron" spend EQUAL time being a left-chiral and right-chiral fermion, on average? Clarification: The electron switches between (-1/2 T3, -1Y) ...
2
votes
1answer
65 views

Does the gravity affect voltage in a circuit?

The electric current is a flow of electrons, which have mass (small, but it is still a mass). So, considering a planar circuit, do the properties of the electric current (voltage, intensity) change ...
0
votes
0answers
21 views

When optically pumping a lasing gain medium with another laser, does Stimulated, or Spontaneous emission dominate?

Much of my reading seems to indicate that laser pumping results in a fluorescent stokes shift but somehow photon vector is maintained. I've seen the phrase "Spontaneous Fluorescence by Stimulated ...
5
votes
2answers
363 views

Can we fully simulate molecular physics?

Is our knowledge of physics complete enough to achieve fully natural simulations of molecular interactions in a computer simulation? How far off are we? Reason for question: I wonder how far we are ...
1
vote
0answers
33 views

Leptogenesis with singlet neutrinos

(i) The Lagrangian of electroweak model extended with right-chiral singlet neutrinos $N_{iR}$ contains the Yukawa coupling term+ the bare Majorana mass term $$f_{\alpha ...
2
votes
1answer
41 views

How do we know what the flavour of the neutrino from a beta decay is?

I have read that because of the conservation of the leptonic number, a neutron should decay into $p + e^- + \overline{\nu}_e$. I don't understand this argument because I have also learnt that the ...
2
votes
1answer
36 views

How many properties like charge, mass etc any quanta or particle must have?

How many properties are required to measure full energy of a fundamental particle? I know $E=mc^2$, but what about charge, spin, etc? Which full equation would give me all parameters of any particle?
3
votes
1answer
75 views

Are there QFTs in which a field cannot produce a real particle?

The usual mantra of a quantum field theory is that real particles (as opposed to virtual ones) are excitations of a field. Is this a necessary property of all (operator-valued) quantum field ...
3
votes
0answers
57 views

Charge conjugation matrix in baryon current

In his paper Calculation of baryon masses in quantum chromodynamics (ScienceDirect), B.L. Ioffe considers currents describing baryons. In equation (13) he gives an interpolating current for the isobar ...
3
votes
2answers
53 views

Adding a tracer to the surface of a water droplet

I have a 2 mm water droplet generated by a syringe and falling down. I am using two perpendicular cameras to capture simultaneous frames from it. I need to track the droplet during the time and ...
0
votes
0answers
23 views

Where does the polarity of particles come from? [duplicate]

Going though current lessons, I can clearly see that some particles, electrons, are charged negatively and other, protons, are charged positively. Where does this polarity come from? Knowing that ...
3
votes
2answers
93 views

Is a wave packet physically realizable as a Fourier series?

In QM a wave packet is modeled as an infinite, or almost infinite, Fourier series, and the Fourier transform provides a transformation between momentum space and position space. To what extent is ...
2
votes
0answers
41 views

particle and antiparticle notation

This may be a very simple question but I'm really confused. If $\psi$ represents a particle (a Dirac fermion). What is an anti-particle represented by? Is it $\bar\psi=\psi^\dagger\gamma^0$ or ...
0
votes
0answers
22 views

Is the continuity (discontinuity) one of the intrinsic properties of all physical objects?

Is the continuity (discontinuity) one of the intrinsic properties of all physical objects? How do we define continuity? Which of the definitions of continuity are used (and why) in physics? This ...
-4
votes
3answers
124 views

how human is affected because of particle accelerator? [closed]

I saw a TV series The Flash which is about physics fiction. What will happen when the human will caome in contact to bombardment of particle accelerator.
1
vote
0answers
27 views

Why do weak interactions give such slow decay rates, if the analog of the fine structure constant isn't signifigantly small?

Intuitively, it seems as though the reason would be a small value for the coupling constant, as the probability for emitting $W^{-}$ bosons would be low. However, it's value is almost the same as the ...
2
votes
0answers
31 views

Discrete Symmetries: Breaking and Preserving

This is not a question, let's list down all the effects resulting from breaking or preserving of various discrete symmetries, on various observables, be it in condensed matter or in high energy. ...
1
vote
0answers
36 views

Charge Conjugation Operator in Supermultiplet

Consider an $\mathcal{N}=1$ left-handed chiral supermultiplet. The particle content is $$L = (\phi\quad e_L) $$ where $\phi$ is a complex scalar and $e_L$ a left handed Weyl fermion. People usually ...
10
votes
2answers
137 views

Black hole “no hair” theorem

The "no hair" theorem (or conjecture), suggests that black holes can be entirely described by their mass, angular momentum and charge. All other details of the BH formation are lost. Is there a ...
4
votes
1answer
64 views

Is the decay $B\rightarrow K^* \gamma$ decay allowed in the Standard Model?

This is my idea of the Feynman diagram of the $B^0$ to a $K^0$ decay: The photon is radiated off by one of the particles, and by $up$ quarks I just mean ($u$,$c$ and $t$) and their antiquarks. how ...
2
votes
1answer
27 views

How can nuclear decay both annihilate and create?

This'll be back to basics for many of you, but here's something I still don't get. How can nuclear decay of an unstable atom both create and annihilate positron-electron pairs? You have an unstable ...
0
votes
2answers
63 views

What is the Weak force?

In this Particle Physics books I'm reading it explains Weak force with Beta Decay, a Neutron turns into a Proton after emitting an electron, so after it emits an electron one of the neutrons ...
5
votes
1answer
168 views

Is the particle reaction $π^- + p \to K^- + Σ^+$ possible?

I'm currently going over some undergraduate exams on particle physics and I'm having problems with a specific reaction, namely $$ \pi^- + p \to K^- + \Sigma^+ $$ which, in my opinion, is not allowed ...
1
vote
0answers
59 views

Mechanism of Supersymmetry Breaking (F-term, D-Term, Mediated)

I will make my question clear. SUSY is broken symmetry because we haven't seen superpartners. As far as I know, there are two mechanism of SUSY breaking, F-term and D-Term. Besides, there are some ...
3
votes
1answer
42 views

The differences of R parity and $U(1)_R$ symmetry

I know that we introduce R-parity to avoid proton decay. But some papers introduce $U(1)_R$ Lepton Number, e.g claudia, thomas. I have questions 1.What is the differences of R parity and $U(1)_R$? ...
5
votes
1answer
99 views

Engineering new particles

I am not a physicist, but I have a somewhat philosophical question regarding particle physics. In chemistry, and biology, there is a notion of synthesis, which has led to the creation of novel ...
0
votes
1answer
35 views

Building blocks of particles in different theories

If I understand it correctly, in most theories in physics we exploit the notion of point, i.e. we have e.g. point-like particles. In string theory, we don't have points, but a notion of string. What ...
6
votes
2answers
603 views

How is antimatter made?

How is antimatter made in laboratory? Can anyone explain, at the particle level, specifically how anti-protons and anti-electrons are made?
1
vote
0answers
50 views

How to construct singlet and other multiplets from two triplets

Let an $SU(2)$ isotriplet operator is given by\begin{equation}\bar{l^c}i\tau_2\vec \tau l=l^T Ci\tau_2\vec \tau l\sim 3\end{equation} and an isotriplet Higgs field \begin{equation}\vec \Delta\sim ...
3
votes
2answers
287 views

Is there a connection between gluons and photons?

I was wondering if there is any sort of connection between a gluon and a photon since they are both considered massless.
2
votes
1answer
135 views

Is this summary of modern theoretical physics correct?

This is not exactly a physics question; it's more of a question about physics. You'll see what I mean in a minute. My understanding of modern theoretical physics is below. What I want to know is: Is ...
5
votes
1answer
377 views

How can mesons have spin greater than 1?

My understanding was that a meson, being made of a quark and an antiquark (spin 1/2) could only have spin 1 or 0, by addition of angular momentum states. I just saw an article ...
1
vote
1answer
73 views

Is it possible to make superpartner of Standard Model live in Mirror World?

In the ordinary Supersymmetry (SUSY), the superpartner of SM live in SM world (matter world). Then we introduce mirror world with mirror particle live there. I would like to make a new concept that ...
10
votes
2answers
126 views

Why do fermions come in generations, but not bosons?

Why does the $1/2$ spin of fundamental fermions (electrons, quarks, and neutrinos) split them into three variants that differ only in mass, while the integer spins of massless fundamental bosons (e.g. ...
4
votes
0answers
25 views

What are hadronic uncertainties?

I am reading articles about recent findings at CERN and the possibility of New Physics contributions, and they keep saying that the discrepancies may be due to hadronic uncertainties... What are ...
1
vote
1answer
63 views

How the neutron magnetic moment was measured?

How was the neutron magnetic moment measured? Was the antineutron magnetic moment measured too?
3
votes
2answers
375 views

What is meant by the spin of a particle? [duplicate]

I have been studying that electrons have quantum number called spin quantum number(s), this number can have either +1/2 or -1/2 value. If s=+1/2, the spin is clockwise and if s=-1/2, the spin is anti ...
6
votes
0answers
208 views

Integration & bremsstrahlung calculation

In this paper (relevant pdf section) that I'm reading, involving the calculation of bremsstrahlung in electron proton scattering (diagram below), the author calculates the integral over outgoing ...